Rough Idle......Tried Searching

[TruPuertoRican87]

Ok I have a s13 with a KA24DE DOHC swap from a s14. I bought the car like this from this guy up in Daytona Beach. About two weeks about I bought the car it would idle real rough sometimes at stop lights and stall while I was turning. I took it to my mechanic and he told me it could most likley be the MAFS, So I bought another one installed it and adjusted the ICV. So then it started to run worse idling even harder. So I put the older MAFS back in and it works fine but still idles and stalls out occassionally. Now my mechanic is telling me it could be the ICV. I dont wanna spend no more money then what I have to on this. So if somebody could please point me into the right direction, it would be GREATLY appreciated.

[S13FASTBACKSR]

does the idle jump around/fluctuate? or does it just all the sudden drop down until it dies out? and does the screw have any effect on the idle when you turn it? if it does fluctuate and the idle screw has no effect then it is most likely your iacv..you could always check for codes on your ecu as well..if you need to know how to do this let us know

[TruPuertoRican87]

Well when we took it to my mechanic and swapped out the MAF we ajusted the screw but then it seemd to be worst! It would shake harder. So we swapped out the MAFS to the old one and it got a little bit better. When I first turn on the car it seems to idle great. But after a little driving, while im stopped at a light it idles rough most of the times.

[S13FASTBACKSR]

have you adjusted the screw with your old maf in? the maf you have in now i mean..did you adjust the screw with that maf and did it have no effect? if you are not running rich then your maf is probably not bad but it could be dirty..try cleaning it with electronic cleaner...are you having any other problems besides bad idle?

[TruPuertoRican87]

Yeah sorry I forgot to mention I been running rich since i bought the car. It throws really thin white smoke when it idling rough. But umm we ajusted the screw with the MAFS that I bought then when i ran crappier i put the old one back in w/o ajusting the screw.

[S13FASTBACKSR]

well first try adjusting the screw..probably wont do anything though so dont get your hopes up..second white smoke means you are not burning rich..try doing a compression test clean your iacv with carb cleaner and check for codes on your ecu..if you need to know how to do these things just ask..good luck

[sumoboi7]

hey im new to nico to but ive had the problem you are having..... what had happened was the coolant sensor was dirty and coroded so i ended up having to order a new one and having it put in. what happens is that when the sensor is not reading properly it may think that the engine is running to cold or to hot and there fore send more or less gas then needed so yours is probably thinking that your car is running to hot so it is sending less gas therefore shutting your car off. thisis just my guess at whats happening but my car did this to and after that it was all fine... so i hope you figure it out.. the guy in the thread before this one had a similar problem..

[S13FASTBACKSR]

yes also a possibility. when my temp sensor went bad i could not start my engine when warm because the ecu could not read the sensor so it thought the engine was cold and therefore more fuel was dumped in...however in your case this could be opposite and like sumoboi said not enough fuel.

[emperor_lunchbox]

Do you have timing rattle?I have this problem with my S13 and the only thing left it timing, I replace the TPS Senser, IACV, fiddled with the screw, checked every hose twice, adjusted everything you could think of. I have spent nearly 500$ and thus far it proves fruitless. It's almost cheaper to get a KA swap. Ha.

The only thing left is timing, if you have some timing rattle it's possible you could have jumped a tooth. At least that's what I hear...

[lowviscosity]

NO KA swap does not work tried that after a mechanic ****ed up my engine with this problem.... it something else like he said above possibly coolant sensor. I need to try that since my new KA is giving me a little trouble, just every once in a while. for the most part its great and then bam After $1400 I'm still in the same **** hole

And no its not timing unless my second KA engine did the same thing the first did, and jumping time is REALLY difficult on these cars and VERY RARE i've heard... and it does it on an off and on basis if it jump timed it would be constant.

[240fstbak]

i had a rough idle problem and i changed spark plugs and fuel filter. Solved the problem. It came bak, replaced o2 sensor and 1 clogged fuel injector. Now my 240 runs perfectly.

[DjPantsSpecR]

My s14 KA swapped 92 also had this nasty rough idling problem. it was an automatic so it would sit ifne at a light for a while, but then the idle would drop and the car would buck at about 500 rpm. occasionally it would die.

The coolant temp sensor was out of spec. it caused the same problem you get whne you unplug the cts. a huge gain in horsepower at about 5300 rpm. and by huge gain i mean big bump in a seriously weaken power curve. unplug your sensor and you'll know what im talking about.

this only helped the problem a little bit, but what i found was a vacuum leak. the largest vac line on the EGR system had a large hole in it. the line is about three to four inches long and it makes a 90 degree bend. the bend eventually mkaes the line fatigue and break. ive had three of these break. problem solved as soon as i fixed this vac leak. it also helps to have a reasonalbly functioning EGR valve....

its worth a shot, its easy to develop a big vac leak somewhere and not necessarily notice it.

[Dattebayo]

Download the FSM. CLICK HERE

Follow the troubleshooting procedures listed in the EF & EC section on page 61 (Diagnostic procedure #3).

I cant believe you couldn't find anything on this in the archives! This subject of "bad idle" comes up a million times a year! Maybe you should try and narrow your search variables next time.
Modified by 2BN_S13 at 10:08 AM 9/4/2006

[jmwenick]

I'm having the same problem, S14 in a S13. Rough idle, but it drives real nice besides the idle. I changed both coolant sensors and its not that. Timing is at 20*. o2 sensor is fairly new, so I don't think its that. I should hook up an adjustable FPR and see what my fuel pressure is. I have a walbro 190 in it so maybe the pressure is too high. I also am going to swap the spark plugs tonight. One more thing, I have a plug thats not hooked up in the back of the intake manifold. You guys have that also?